Extra Options
Finish the game with a High ranking and a new options menu should appear.

Unlock Gallery
Complete the game once on any difficulty level. The game will auto-save and you will now have access to ''Gallery'' mode. Keep on playing the game and taking different paths in each stages to unlock more artworks in ''Gallery'' mode

Gunpods

If you beat the game on easy without continuing you will get a ship that looks kind of like one of the first car things at the beginning of the first level! If you beat the game in hard mode you will get a ship that has 9,999 for the gunpods.

Secret Weapons

Juno: There are two stages where you can get the Juno.
(Like the Vulcan but stronger, not as much ammo as the Vulcan though)

Stage 4:
When the large boat pops out of the water, destroy the body first. Then destroy the tower. After the tower is destroyed you get the Juno.
Stage 7:
Destroy all three red fighters and you will get the Juno.

Flash: There are stages where you can get the Flash.
(Laser that goes through the enemy hitting things behind it as well, powerful but low ammo)

Stage 3
After you destroy the spider mid-boss, destroy the core that drops the flyers and immediately destroy everything that falls from it. The Flash will then drop from the core.
Stage 5
Take apart the giant robot mid-boss Piece by Piece and then destroy it. It will then throw or kick a red box containing a Flash.

Mosquito: One stage has this guided missile.
(Guided missles, hard to control without killing yourself)

Stage 4
After destroying the mid-boss in the water, pick up the spreader in the boxes and switch it to the top part of your fighter. In this small maze-like section, move all the way down until you see a box behind you. Shoot the box to get the Mosquito.

Python: One stage has this chain bomb.
(Chain bomb that detonates on contact or after few second)

Stage 5
Destroy the large vehicle in the background in the first part of the stage with the Wasp and if you can reach the Python it leaves behind, then you get the Python.